assigned to users and working with Yootheme

@webteam4u

We have checked your requirement.
Can the location be assigned to a Joomla user?
Yes the location can be assigned to user using either community builder or joomsocial or easysocial.you can chose either of them and we will give support if in any case you find any issue.
If so, is it possible to assign multiple locations to one user?
That need customization as user id is unique in our database.one user id cannot have multiple location in current design.

Can 'My maps location' be used with Yootheme builder pages and with fields?
These thing can be done using module.
is there any specific support you want in this we can work on enhancing my map locations for yootheme builder.